1. Field of the Invention
The present invention relates to an oil pressure signal output device and more particularly to an oil pressure signal output device responsive to signals produced by manual operations inside a vehicle or by external operations including radio control or others from outside the vehicle to output oil pressure signals according to the operations to a hydraulic apparatus.
2. Discription of the Related Art
The driver""s cab of working vehicles including a hydraulic excavator is equipped with an oil pressure signal output device for outputting a pilot pressure oil according to the operations of an operation lever or others. As for this oil pressure signal output device, an operator sways an operation lever back and forth, rightward and leftward, or obliquely to manipulate it manually, thereby manipulating pressure reducing valves through the respective pistons. Then, the pressure reducing valves output oil pressure signals of pilot pressure oil to hydraulic apparatuses according to a quantity of the operation. The actuation of the hydraulic apparatuses controls the operations of a vehicle or working machine.
Now, FIG. 25 is a sectional view of a manual oil pressure signal output device having an operation lever. In the manual oil pressure signal output device 50 (hereinafter referred to as PPC valve 50), the single operation lever 7 is swayed back and forth, or rightward and leftward, whereby four pressure reducing valves 14 corresponding to four pistons 4, 6 respectively (the pistons 3, 5 are not shown) output oil pressure signals according to the displacement of the pistons, more specifically pilot pressure oil, toward operating valves (not shown), which is a hydraulic apparatus, to switch the operating valves. Controlling the operating valves controls the operation of a hydraulic motor for driving a vehicle, a hydraulic cylinder for actuating a working machine, or the like.
An electric oil pressure signal output device for outputting pilot pressure oil in response to electric signals may be provided. This electric oil pressure signal output device is used in a case where an operator manipulates a remote operation device at a place away from a vehicle, such as the case of working at a disaster-stricken district, to activate a working vehicle. Based on the control commands sent from the remote operation device by radio, the controller outputs a control command current to the electric oil pressure signal output device and the electric oil pressure signal output device outputs pilot pressure oil with a pressure according to an amount of this command current.
FIG. 26 is a sectional view showing the electric oil pressure signal output device. Individual electric oil pressure signal output devices 60 are provided corresponding to the four pressure reducing valves 14 of the PPC valve 50 respectively. When the electric oil pressure signal output devices 60 are manipulated remotely, the operation of a hydraulic motor for driving use, a hydraulic cylinder for working machines, or the like can be controlled. Each electric oil pressure signal output device 60 has a electromagnetic, pressure-proportional pressure reducing valve 27, which is actuated by a solenoid, and it is hereinafter referred to as EPC valve 60. In the EPC valve 60, the thrust proportional to an amount of command current flowing through the solenoid coil 25 acts on the plunger 26 in the direction of U to actuate the spool 28, thereby outputting pilot pressure oil with a pressure according to the command current.
While FIGS. 25 and 26 use the same reference numerals for constituent elements as those of the elements in the description of the embodiments of the invention, their description are omitted here.
As shown in FIG. 27, inside driver""s cab of a vehicle, there are provided a PPC valve 50 and an EPC valve 60 separately, and further separately provided a shuttle valve 30 connected to the PPC valve 50 and EPC valve 60. The shuttle valve 30 outputs pilot pressure oil from one of the PPC valve 50 and EPC valve 60, which is under higher pressure than the other. This pilot pressure oil is input an operating valve for controlling pressure oil to be supplied to a hydraulic motor or a working machine. Therefore, when an operator manipulates an operation lever or a remote operation device, the operating valve is switched by the pilot pressure oil, thereby enabling a vehicle to run or a working machine to be actuated.
However, in the above conventional construction, when a PPC valve 50, EPC valve 60 and shuttle valve 30 are provided as separate units inside driver""s cab of a vehicle, it is required to connect the PPC valve 50, EPC valve 60 and shuttle valve 30 through piping including a hose, and thus a large occupied area is needed. This causes the problem that the remaining space except these hydraulic apparatuses in a driver""s cab becomes relatively small, which makes it difficult to place other vehicle-mounted apparatuses.
The invention was made in consideration of these actual conditions, so it is a first challenge of the invention to provide an oil pressure signal output device using a small occupied area, thereby reducing an occupied area of hydraulic apparatuses in a driver""s cab to make a space except hydraulic apparatuses larger.
As a solution thereof, we have offered suggestions, Japanese patent application No. 2000-340612 and 2000-346711 (JP-A-2002-147407).
In the meantime, in recent years, it has become common practice for working vehicles including a hydraulic excavator to be mounted with various attachments including a clamshell bucket or a breaker in addition to a working machine, such as a regular excavator and thus the contents of works have spread. For this reason, an operating valve for controlling a hydraulic apparatus for an attachment use is additionally required, and it is necessary to provide a PPC valve 50 and EPC valve 60 for the purpose of switching this operating valve, and either the set of an electric switch and EPC valve 60, or the set of an electric lever and EPC valve 60 inside the driver""s cab to enable an operator to conduct manual operations inside the driver""s cab and to perform the manipulations by a remote operation device outside the cab. Incident to this, however, the addition of the EPC valve 60 inside the driver""s cab leads to the needs for connecting additional piping with this EPC valve 60, whereby the occupied area of the hydraulic apparatus becomes larger. On this account, providing a new EPC valve 60 for the attachment use inside the driver""s cab causes an additional problem that a space except the hydraulic apparatus relatively becomes smaller.
Further, there may be a case where an attachment is additionally mounted after shipment. Also, in this case, it is strongly desired to provide an oil pressure signal output device which can be easily mounted with an attachment and can be manipulated readily.
The invention was made focusing on the problem and relates to an oil pressure signal output device. Therefore, it is an object to provide an oil pressure signal output device, which permits easy integration of a new EPC valve for an attachment use and manipulation from inside and outside a driver""s cab, and which is capable of making the occupied area of hydraulic apparatuses smaller and a space except the hydraulic apparatuses larger.
To attain the above objects, an oil pressure signal output device according to a first embodiment of the invention includes: a manual oil pressure signal output device for outputting an oil pressure signal based on a manual operation; at least one first electric oil pressure signal output device for outputting an oil pressure signal based on an electric signal; and selecting output means for selecting either an oil pressure signal output from said manual oil pressure signal output device or an oil pressure signal output from said first electric oil pressure signal output device to output the selected oil pressure signal outside, wherein the manual oil pressure signal output device for controlling a first hydraulic apparatus, the first electric oil pressure signal output device and the selecting output means are integrated, a second electric oil pressure signal output device for controlling a second hydraulic apparatus different from the first hydraulic apparatus is removably provided and abutting against the first electric oil pressure signal output device.
According to the first embodiment, in the oil pressure signal output device, the manual oil pressure signal output device for controlling a first hydraulic apparatus (PPC valve), the first electric oil pressure signal output device (EPC valve) and selecting output means (hereinafter referred to as shuttle valves) are integrated; a second EPC valve for controlling a second hydraulic apparatus different from the first hydraulic apparatus abuts against the first EPC valve and is removably provided. For this reason, the second EPC valve for the other hydraulic apparatus can be mounted easily and compactly even when an additional (second) hydraulic apparatus for a new attachment is required at the time of or after the shipment. Further, even when an additional second EPC valve is provided, it is not required to connect it through piping including a hose, so that the occupied area of hydraulic apparatuses in a driver""s cab can be reduced. Therefore, it is possible to secure a larger space other than that of hydraulic apparatuses in a driver""s cab.
An oil pressure signal output device according to a second embodiment of the invention includes: a manual oil pressure signal output device for outputting an oil pressure signal based on a manual operation by an operator in a driver""s cab; a first electric oil pressure signal output device for outputting an oil pressure signal based on an electric signal from outside the driver""s cab; and selecting output means for selecting either an oil pressure signal output from the manual oil pressure signal output device or an oil pressure signal output from the first electric oil pressure signal output device to output the selected oil pressure signal outside, wherein the manual oil pressure signal output device for controlling a first hydraulic apparatus, the first electric oil pressure signal output device and the selecting output means are integrated, a pump passage for supplying pressure oil from a hydraulic pump, and a tank passage for draining return oil into a tank, which are respectively brought into communication with a side surface of the first electric oil pressure signal output device, a second electric oil pressure signal output device for controlling a second hydraulic apparatus different from the first hydraulic apparatus can be mounted additionally, and covers for blocking the pump passage and the tank passage are removably provided on side surfaces of the first electric oil pressure signal output device.
In the oil pressure signal output device according to the second embodiment, the PPC valve, the first EPC valve and the shuttle valves are integrated; the EPC valve for a second hydraulic apparatus can be additionally mounted on a side surface of the first EPC valve; and covers are removably provided, so that it is possible to obtain the same actions and advantages as those of the first embodiment and also to manipulate the second EPC valve using an electric lever, switch or the like from outside a driver""s cab. This also enables an additional working machine such as an attachment to be manipulated from outside a driver""s cab and enables the remote manipulation. Further, a new attachment can be mounted easily even after shipment, thereby improving the maintainability.
In a third and fourth embodiments, in addition to the conditions of the first and second embodiments, a bottom surface of the manual oil pressure signal output device and an upper surface of the first electric oil pressure signal output device abut against each other to be integrated, and the second electric oil pressure signal output device is removably provided on a side surface of the first electric oil pressure signal output device.
According to the third and fourth embodiments, a bottom surface of the PPC valve and an upper surface of the first EPC valve abut against each other to be integrated, and the second EPC valve is removably provided on a side surface of the first EPC valve, so that it is possible to install a given number of the second EPC valves on both side surfaces of the first EPC valve easily. Additionally, because the second EPC valve is mounted on the side surface of the first EPC valve, it is not subjected to the interference of the piping for the first EPC valve, so that the second EPC valve can be easily mounted and removed and therefore the maintainability can be improved.
In a fifth to eighth embodiments, in addition to the conditions of the first to fourth embodiments, the manual oil pressure signal output device, the first electric oil pressure signal output device, and the second electric oil pressure signal output device, which are mutually adjacent, are connected through pump passages and tank passages provided inside the respective oil pressure signal output devices and are connected to a common hydraulic pump and a common tank.
According to the fifth to eighth embodiments, the PPC valve, the first EPC valve, and the second EPC, which are mutually adjacent, are connected through pump passages and tank passages provided in their inside and are connected to a common hydraulic pump and a common tank. Therefore, it is not required to add neither pump line nor tank line when providing an EPC valve for manipulating a new attachment and it is possible to easily mount an oil pressure signal output device capable of manipulating a new attachment at the time of and after the shipment. Further, even when a new second EPC valve is provided, the connection through piping including a hose is not required, so that the occupied area of the hydraulic apparatuses in a driver""s cab can be reduced. In addition, the need for adding a pump line and a tank line is eliminated, and it become possible to reduce the number of assembly steps and to improve the maintainability.